1982 300CD Rough Idle, what should I check?

[danok]

200,000 miles; well maintained by previous owner. Frequent oil changes, and maintenance done by certified MB mechanic/guru.

Recently the idle became rough. I changed the main fuel filter and the secondary fuel filter. Removed air cleaner cover and continued to run rough. (It is running so rough at an idle that the whole car shakes. Once it gets up to speed it does OK. Power is less than normal. It is smoking-espescially at startup more than normal, and smells like unburnt fuel. It will die at an idle unless you keep your foot on the gas.)


What else should I bee checking?



Thanks for you input in advance